Liquid Chromatography-High Resolution Mass Spectrometry Analysis of Platelet Frataxin as a Protein Biomarker for the Rare Disease Friedreich’s Ataxia

Lili Guo, Qingqing Wang, Liwei Weng, Lauren A. Hauser, Cassandra J. Strawser, Agostinho G. Rocha, Andrew Dancis, Clementina A Mesaros, David R. Lynch, and Ian Alexander Blair; Anal. Chem., Just Accepted Manuscript DOI: 10.1021/acs.analchem.7b04590 Publication Date (Web): December 22, 2017

Frataxin is undetectable in serum or plasma, and whole blood cannot be used because it is present in long-lived erythrocytes. Therefore, an assay was developed for analyzing frataxin in platelets, which have a half-life of 10-days. The assay is based on stable isotope dilution immunopurification two-dimensional nano-ultrahigh performance liquid chromatography/parallel reaction monitoring/mass spectrometry. The lower limit of quantification was 0.078 pg frataxin/μg protein and the assay had 100% sensitivity and specificity for discriminating between controls and FA cases. The mean levels of control and FA platelet frataxin were 9.4 2.6 pg/g protein and 2.4 0.6 pg/g protein, respectively. The assay should make it possible to rigorously monitor the effects of therapeutic interventions on frataxin expression in this devastating disease.